Currently, an ADC is an essential core component of a measurement instrument, and is widely applied in fields such as precision instruments, testing and measurement, space and aviation, and communications. A frequency response is a key feature parameter of the ADC. Currently, an ADC amplitude/frequency response test technology is mature, but there are still a lot of problems to be resolved urgently in a phase-frequency response test technology. An ADC phase-frequency response directly affects real-time quality of acquired signals, and further affects ADC-based measurement instrument performance. In particular, in fields such as real-time motion control, real-time monitoring, and inertial navigation, it is required that real-time quality of signals acquired by an ADC should be higher. By performing an ADC phase-frequency response test, delay correction or compensation can be implemented for the signals acquired by the ADC, so that a measurement error caused by ADC acquisition is reduced. Therefore, research on an ADC phase-frequency response test method is of great significance.
Currently, in an IEEE ADC test standard, it is recommended that an input step signal should be used to implement an ADC phase-frequency response test, and that an ADC output response under the step signal should be acquired and processed to implement the ADC phase-frequency response test. A specific test principle is: acquiring an output response of an ADC under a step signal input within a sufficiently long time; obtaining a phase spectrum of the output response by performing a discrete Fourier transform (DFT), and avoiding discontinuity of phase wrapping in the DFT transform by means of phase unwrapping; and implementing an ADC phase-frequency response test by using an unwrapped continuous phase spectrum. This test method can implement an ADC phase-frequency response test in a specific frequency range. However, an uncertain time delay caused by a difference between a signal start recording time and a step signal conversion recording time has an impact on the method, and the time consumed by the DFT transform increases apparently as a quantity of sampling points of the output response increases. In addition, in this method, a maximum test frequency cannot exceed half of a maximum sampling frequency of the ADC.
Therefore, in view of disadvantages of the conventional ADC phase-frequency response test method, such as limited test precision and a limited test frequency range, the present disclosure provides an ADC phase-frequency response test method featuring high test precision, a high speed, and a wide frequency range with frequencies that may be higher than a maximum sampling frequency of an ADC, and capable of implementing a test on multiple channels simultaneously.